Small electronic circuits are often used in conjunction with high frequency signals. However, some transmission materials used in such circuits exhibit lossy transmission characteristics with respect to high frequency signals. For example, signals transmitted at 3 to 4 GHz over a small portion of FR4 substrate may experience 30 to 40 dB of loss.
Circuit designers may use analog or digital filters to compensate for the loss. Digital filters usually provide a better combination of linearity, power consumption and scalability than analog filters. However, before a digital filter can filter an analog signal, the signal must be converted to a digital signal by an analog-to-digital converter.
Signals may be transmitted using many signaling schemes. One known scheme is differential current-mode signaling, in which data is represented by a difference between two currents carried by (usually) adjacent signal lines. Differential current-mode signaling is known to result in better common mode noise rejection, power-supply noise rejection, and less return current than other signaling systems. Signaling may be further improved by terminating each signal line with an impedance equal to the intrinsic line impedance. Such impedance matching reduces reflections and crosstalk within the signal lines. Unfortunately, additional elements required for the termination impedance require additional power.